In general, a putting motion in golf is mainly performed at a final stage of inserting a golf ball into a hole cup and, therefore, one of motions requiring high concentration and precise directivity taking consideration of an inclined plane of a putting green.
Meanwhile, since a putting green of a golf course is designed with inclined planes in a variety of shapes around the hole cup, it is absolutely necessary for a golfer to accurately read a slope between a position where the golf ball is placed and the hole cup at the time of putting, thereby enhancing a success rate of the putting. However, most golfers are not able to read the slope of the putting green, thereby experiencing difficulty in putting.
There are many products and patents that indicate a golf putting direction as an auxiliary means to overcome the difficulties in putting as described above, thereby improving the accuracy of the putting. However, there is a problem that the accuracy of the putting is decreased due to a mismatch between the direction indicated by each product according to the conventional art and the center location and directivity of the golf ball.
Meanwhile, as a means for solving the above-mentioned problems, a technique of using a spirit level is disclosed, wherein the spirit level measures the slope using a movement of a bubble forced to be formed after filling a transparent cylindrical container with a liquid.
However, in the case of using the above-described spirit level using the bubble, the vertex of a tilt can be identified because of the cylindrical spirit level, but there is a problem that it is difficult to identify the tilted angle and direction. Particularly, since the bubble of the above-mentioned spirit level moves only in an upward direction, it is not possible to identify the degree of the angle that the bubble is tilted at by exactly measuring the bubble by a scale, even if there is a movement of the bubble. Accordingly, there is a problem that it is not possible to identify exact degrees of the angle, thereby allowing a slope to be only approximately identified.
In addition, in the conventional art, there is a case in which a spirit level is attached to a putter. In this case, however, there is a problem that attaching the spirit level to the putter is onerous and measuring a slope in a direction in which the ball is to be sent is complicated. That is, when the spirit level is attached to the putter, it not only violates golf rules but also makes the putter difficult to be in surface contact with the putting green, and there is a problem in that the slope of the putting green can be measured only by moving the putter in every direction.
In addition, in the conventional art, an electronic putting slope measurement device is in circulation. However, a digital technique indicating putting slope and vertical slope allows the golfer to read an indication that is a digitized slope angle of the product, and to recognize only the figure of the slope angle in golfer's mind. It may be possible for the golfer to putt the golf ball roughly toward an inclined plane while drawing the angle of the slope of the golf ball in his or her mind, wherein the angle of the slope of the golf ball is taken by eye with the actual hole cup direction as the reference line, thereby causing a difficult problem of letting the golf ball set at an exact slope angle for performing the putting.
In addition, in the conventional art, the gears of the direction indication needle and the gears of the direction converter are engaged with each other and the magnification of the direction angle is determined by the ratio of the gears, respectively, whereby the accuracy of the angle of the putting direction is maintained. However, because a structure of the saw-toothed gears like these is formed to be very small, a dislocation between the gears occurs even in a small external impact, thereby causing a problem that a new alignment is required every time.